For instance, as recited in patent document 1, various technologies are conventionally proposed relating to a microcomputer system using ports of a microcomputer to detect the states of a plurality of switches.    Patent document 1: Japanese Patent Application Laid-Open No. 2001-255983
The microcomputer system described above is required to detect the states of a large number of switches with as few ports as possible in order to simplify a circuit configuration.
It is also required to simplify a process of detecting the states of switches in the microcomputer in order to reduce power consumption.